Who would you prefer to have on your team?

Lux vs Morgana

Who's better?
Both snare, ranged, kinda supporty, good in a duo lane or a solo lane.
Morgana has a kind of better shield, since it resists CC, But Lux can shield multiple people and snare two.
Both have team-wrecking supports, though Morgana's might be a tad better, lux's has a short cooldown.
Both have an AOE dps thing.

Who would you prefer to have on your team? (AKA, Who should I buy?)

Also, for you who comment, who would win in a fight?

EDIT: Additional question
Which one is more difficult to play? Lux or Morgana?
I'm assuming Lux. More skillshots, etc.
Just throwing this in for you commenters.

Lux was a bit weak compared to morg on release. But then had some buffs that put them on more even ground. It was a play style choice. Lux=ranged poke/support. Morg=short ranged sustain/support

But morg was recently buffed inexplicably. Putting her into ban status in like 80% of games. So when you do get to play her, shes really strong. but also banned more often then not in draft mode.
Upcoming patch will be nerfing alternate aspects of her, instead of just reverting the unneeded buff.
Hard to tell if it will make her playable again.

Lux has a large issue with being unable to kill tanky dps, even when fed. Morg puts out ALOT more damage. 300+.9ap scaling on her binding, vs lux's 260+.7 Puddle increases magic damage, and ult hits harder, and with buff, often more targets. Lux will often hit a place where, she just doesn't have the firepower to kill a sion/cho/mundo/garen, etc. If you team is winning hard, you'll be fine. but a close game with Lux often leaves her in a bad place. A losing game, is generally unwinnable, as she can't come back from that damage deficit. (she can steal barons, dragons, golem pretty well.)

Morgs other claim to fame is of course the shield. Which can be broken op when combined with certain champs. For example, akali, katarina, nocturne. there are a number of champs that will just run wild with the cc shield.

deathcap rush on lux is very popular due to this. If she falls behind the curve in ap, she'll never catch up. Deathcaps high ap, lets her get ahead. She can stack mejais pretty well too from assists.